This document discusses decreasing x-ray exposure in complex coronary total occlusion (CTO) procedures. It notes that CTO procedures can result in several grays of radiation exposure to the skin of patients, increasing their risk of radiation injury. It also notes that without proper protection, interventional staff could receive milligrays of exposure per procedure to the lens of their eyes, increasing their risk of radiation-induced cataracts. The document recommends maintaining radiation doses as low as reasonably achievable for both patients and staff by following diagnostic reference levels, avoiding injuries through clinical follow-up of high dose procedures, and using protective equipment to reduce staff occupational exposures.

1. Decreasing X-ray
exposure in CTO
procedures
Eliseo Vano
(JM Fernandez, RM Sanchez, JI Ten)
eliseov@med.ucm.es
Friday Sept 26, 12:25-12:50
1
San Carlos University Hospital. Medical Physics Service.
Radiology Department. Complutense University. Madrid.

2. Content
1. Level of patient exposure during CTO
procedures. Are dose values in your cath
lab, “acceptable” or are they “too high”?.
2. Staff radiation risk needs also be
considered.
3. International recommendations and
European regulation.
2

3. Patient and staff doses
• In some complex CTO procedures several
Grays (Gy) could be accumulated at the skin
of the patients with a risk of radiation injuries.
• If staff is not properly protected, some mGy per
procedure could be the dose at the lens of
the eyes for complex procedures and the risk of
radiation induced cataracts exists.
• The new annual occupational dose limit for the
lens of the eyes is 20 mSv (instead of 150 mSv).
3

4. A good management of patient and
staff radiation doses
• Maintain dose values as low as reasonably
achievable considering the clinical benefit of the
procedure (for patients and staff).
• Work under radiation dose limits (for
professionals) and use “Diagnostic Reference
Levels” (DRLs) for patients.
• Avoid radiation injuries and establish a clinical
follow-up for high dose procedures.
4

5. Managing patient
radiation doses
5

6. 6
Dose Area Product (or KAP) and
cumulative dose (kerma)

7. 7
Interventional Reference
Point (now “patient
entrance reference point” in
IEC 60601-2-43, 2010)
7
Patient entrance
reference point

8. 88
Cumulative dose of 2000
mGy at the patient
entrance reference point
may involve very
different peak skin doses
Peak 100
mGy Peak 1500
mGy
Peak 800
mGy

9. 9
Europe
2003
Diagnostic Reference Levels (DRLs)
for Cardiology

10. • To update reference values for the main radiation dose
parameters for coronary angiography (CA) and
percutaneous coronary intervention (PCI).
• Multicenter, nationwide French survey, with retrospective
analysis. Radiation parameters registered for 33,937 CAs
and 27,826 PCIs performed at 44 centers during 2010.
• Updated diagnostic reference values are established.
KAP, 45 Gy cm2 for CA and 95 Gy cm2 for PCI.
10
France
2014

11. 11
Spanish DRLs values :
32 Gy cm2 for CA and
76 Gy cm2 for PCI
Median values at the
SCUH in 2013
CA: 31 Gy cm2
PCI: 54 Gy cm2
Spain
2014

12. 12
CTO requires around 35% more radiation dose
than standard PTCA

13. 13
63.5
72.0
84.4
99.0 96.0
73.0
0.0
20.0
40.0
60.0
80.0
100.0
120.0
Gycm2 KAP (median) for total occlusion procedures SCUH
Total sample 670 CTOs procedures at the SCUH

14. 14
Total sample 670 CTOs procedures at the SCUH
During 2013, CTO resulted in 60% more Kair than PTCAs

15. DOLIR (Dose On Line for Interventional Radiology)
5 Vascular labs;
9 Cardiology labs from 5 University Hospitals in Madrid
Hospital Clínico San Carlos
Hospital U. La PrincesaHospital U. Puerta de Hierro
Hospital U. Severo Ochoa
Hospital U. Principe de Asturias
6
Madrid
Area

16. Comparison of
CAK (upper graph)
and Life CAK
(lower graph)
corresponding to
the same patients.
Note as indicated
with an arrow a
procedure with
less than 4 Gy in
CAK and nearly 10
Gy with Life CAK
Percentage with
Kair ≥ 5 Gy 0.6 %
Percentage with
Kair ≥ 5 Gy 1.6 %
But for CTO this
value is 10%

17. 13.0 Gy
-40
-30
-20
-10
0
10
20
30
40
50
-120 -70 -20 30
Angulation
Rotation
Area of the skin dose injury
Chronic total occlusion
procedure made at the SCUH
on October 2010. Cinical
follow-up. Image 45 days
after the procedure.
Importance of a patient dosimetry and clinical follow-up program in the
detection of radiodermatitis after long percutaneous coronary interventions.
Vano E, Escaned J, et al. Cardiovasc Intervent Radiol. 2013 Apr;36(2):330-7. 17

18. Real time skin dose map (Philips prototype)
CTO procedure at the SCUH May 2012 18

19. Toshiba skin dose map
19

20. 20
Skin dose map from RDSR using DOLIR (Sept 2014)

21. Radiation risk for staff
New threshold for lens opacities
and new occupational dose limit
for professionals
21

22. "Risk for radiation induced cataract for staff in
interventional cardiology: Is there reason for concern?“
O Ciraj-Bjelac, MM Rehani, KH Sim, HB Liew, E Vano, NJ Kleiman
Catheter Cardiovasc Interv. 2010; 15;76(6):826-34
Survey in Malaysia (April 2009), the prevalence of radiation
associated posterior lens opacities was 52% for interv.
cardiologists, 45% for nurses and 9% for controls.
22
Survey in Latin America 2010, posterior subcapsular lens
opacities found in 50% of interventional cardiologists
and 41% of nurses and technicians compared with
findings of similar lens changes in < 10% of controls.
J Vasc Interv
Radiol
2013;24:197–204

23. 23
Subcapsular posterior cataract
observed by slit lamp
biomicroscopy using direct
illumination and retroillumination
(on the right) after 22 years of work
in a catheterization laboratory
without proper protection.

24. 24
The participant’s curve (solid
line) matches the curve of the
hypothetical normal contrast
sensitivity function (dotted
line). On the right, contrast
sensitivity curve for one
subject with a significant loss
of contrast.

25. 25
Occupational
doses in real time
at the cath lab
Electronic
active
dosimeter

26. CTO resulting in 2990 μSv
(scatter dose) at the C-arm for
152 Gy cm2. Without protection,
lens doses could be around 2
mSv in a single procedure
Need to use proper
occupational protection
for the lens of the eyes

27. 27
(median values, from chest dosimeter, with ceiling suspended screen)
For Cardiology: 0.36 µSv/(Gy cm2) using protection

28. International
Recommendations and
European Regulation
28

29. Published in 2000
29

30. 30
Published in 2013
• Radiation dose data should be
recorded in the patient’s medical
record.
• Use institution’s trigger level and
clinical follow-up for early
detection and management of
skin injuries.
• Suggested values for the trigger
level are a peak skin dose of 3
Gy, a KAP of 500 Gycm2, or Kair
of 5 Gy.
• Training programmes in RP
should include both initial
training and regular updating
and retraining.

31. European Directive 2013/59/Euratom
• The limit on the equivalent dose for the lens of the eye
shall be 20 mSv in a single year …
• DRLs also for interventional procedures and regular
review. If consistently exceeded appropriate corrective
action is taken without undue delay.
• Consideration of occupational doses in justification and
optimization.
• Dosimetric information in all diagnostic systems and
transfer to the patient report. Mandatory for all
interventional and CT procedures.
• Registry and analysis of all the accidental or unintended
irradiation of patients.
31

32. • Promote individual patient dose registry.
• Periodic comparison with local (or
European) DRLs and promt corrective
actions if appropriate.
• Clinical follow-up for potential skin injuries
if individual patient dose values are over
the trigger levels.
• Follow up of staff doses and periodic lens
dose evaluation.
32
Conclusions and recommendations